1. Field of the Invention
The present invention relates generally to identifying users based on location and, more specifically, identifying users based on each user's location while protecting the user's privacy.
2. Description of the Related Art
Marketers and product developers rely on consumer surveys to measure performance of ads, products, and services. Often such surveyors wish to select survey participants based on where, geographically, the participants have been and what time they were there, e.g., drivers who passed a billboard during evening rush hour, or people exposed to pollen in some region and taking a particular allergy medication. Similarly, marketers often seek to present other offers, e.g., a discount, to users based on the user's location history. However, identifying candidates based on location is difficult, because for relatively strict criteria, only a small portion of the general population will meet the criteria, e.g., the set of above-mentioned drivers who also take a particular type of blood-pressure medication related to the an ad on billboard. Exacerbating the problem, many potential candidates are hesitant to reveal their location history for privacy reasons.